Over the past few decades, there has been an increase in the awareness of health among individuals. Taking supplements has become the norm to compensate for poor-quality diets as a result of the boom in the fast food industry. 

Essential fatty acid supplements are one of the most common and sought-after due to the increase in the number of studies justifying their functional properties.

What are essential fatty acids (EFA)?

Essential fatty acids are those fats that, as the name suggests are indispensable for the functions of the body. They cannot be synthesised by the body and must be obtained through an external source. Omega 3 and Omega 6 are the 2 families of EFA.

Omega 3 fatty acids (⍵-3 fatty acids)

⍵-3 fatty acids have a common double bond in the third position from the function methyl group. ⍵-3 fatty acids are present in the forms of:

• ALA (α-Linolenic acid) – Found in flaxseeds, hemp seeds, soybean oil, canola oil and chloroplast of green leafy vegetables.
  
  
• EPA (eicosapentaenoic acid) – This is the parent of the other 2 omega-3 fatty acids. It is present in oily fish as well as fish oils. The concentration of omega 3 and omega 6 may vary from 39–50% in freshwater and saltwater fish.
  
  
• DHA (docosahexaenoic acid) – This is the major omega-3 fatty acid responsible for the brain (65% of the brain is made of fat, of which 50% is EFA) and retinal health. It is found in fish oil and red-brown algae.
  
  

Dietary status of omega-3

ALA by nature is sensitive to light, heat and oxygen. It can become toxic if not protected. It may get destroyed five times faster than linoleic acid.  

On average, the intake of omega-3 fatty acids has decreased, and the current intake is less than 20% of our ancestor’s diet. 95-99% of the global population consumes less than required omega-3 fatty acids. 

Functions of omega 3

1. Brain and eye health

• DHA is the most abundantly present omega 3 in the central nervous system and retina.
  
  
• It is responsible for neurotransmission, neuroplasticity, and signal transduction.
  
  
• It increases the concentration of acetylcholine and serotonin in the nervous tissues.
  
  
• It plays a crucial role in prenatal and early postnatal brain and visual development.
  
  
• Supplementation of omega 3 during pregnancy is associated with cognitive, visual, and brain development of the foetus.

2. Behavioural and psychiatric health

• Low levels of EPA and DHA in children are associated with ASD (Autism spectrum disorder) and ADHD (Attention deficit hyperactivity disorder).
  
  
• Balancing serum levels of EPA and DHA supposedly helps improve behavioural and psychiatric conditions.
  
  
• The International Society of Nutritional Psychiatry Research promotes the use of omega-3 PUFAs for preventing depression in pregnant women, children and the elderly. They suggest pure EPA or an EPA: DHA ratio of 2:1.
  

3. Anti-inflammatory

• EPA and DHA have anti-inflammatory effects. They majorly mediate this process by decreasing the production of AA-derived eicosanoids.
  
  
• Increased EPA and DHA intake increases the cellular concentration of EPA and DHA. They can directly act on inflammatory cells to reduce inflammation.
  
  
• They also decrease levels of inflammatory markers such as cytokines, chemokines, acute-phase proteins and other molecules.
  
  

4. Cognitive decline

• There is an indirect relationship between DHA intake and the risk of dementia and Alzheimer’s disease.
  
  
• A study revealed, higher plasma phosphatidylcholine DHA is associated with a 47% lower risk of developing dementia and a 39% lower risk of Alzheimer’s disease.  
  
  
• However, it is important to note that the effectiveness of omega 3 will vary based on the disease of concern.
  
  
• The use of omega 3 during the early stages of Alzheimer’s disease is most beneficial.
  
  
• Supplementing omega-3 PUFA in healthy older people can benefit the white matter, grey matter and vascular parameters of the brain.
  
  

5. Cardiovascular diseases

• Several studies have shown that a higher intake of DHA and EPA helps in reducing the risks of several heart-related diseases. In other words, EPA and DHA reduce the risks of any coronary-related diseases by 18%.
  
  
• Consumption of 1g/day of EPA and DHA is associated with 9% and 7% reduced risks of myocardial infarction and total coronary heart disease.
  
  
• However, it is important to remember that EPA and DHA have different effects for different diseases, but the studies are not conclusive of the mechanism of beneficial effects.

Omega 6 fatty acids (⍵-6 fatty acids)

⍵-6 fatty acids have a common double bond in the 6th position from the function methyl group or the ⍵-6 position. ⍵-6 fatty acids are present in the forms of:

• Linoleic acid (LA) – The body converts LA into fatty acids as and when essential. LA is present abundantly in safflower, sunflower, and corn, and in moderate amounts in soybeans, sesame and almonds. LA is present in the least quantities in canola, peanut and olive oil.
  
  

• Gamma linoleic acid (GLA) – It is present in primrose oil, black currants, borage, organ meat and human breast milk.
  
  

• Di-homo gamma-linolenic acid – It is synthesised in the body from GLA.
  
  
• Arachidonic acid (AA) – It is present in animal products such as meat, eggs and dairy products. 
  

Dietary status of omega-6

The consumption of omega-6 in the diet is quite abundant and supplementation is not usually required.

High consumption of LA and lower consumption of omega 3 in the diet is associated with increased inflammation, hypertension, heart disease, stroke and blood clots. High LA can retard the conversion of ALA to EPA and DHA by inhibiting desaturase (an enzyme that regulates the unsaturation of fatty acids). Desaturase also decreases with age.

Functions of omega 6

1. Skin health

Linoleic acid helps with the structural integrity of the skin, as it is an important part of ceramides. The skin has less ability to convert LA to AA. Different PUFAS play an important role in skin health, especially in inflammatory skin disorders by altering the levels of inflammatory and anti-inflammatory eicosanoids (they activate substrates for lipid mediators). The combined treatment of omega 6 and omega 3 is helpful for inflammatory skin diseases. There isn’t sufficient research to suggest the individual capacity of omega 6 in the treatment of skin disorders. 

2. Cholesterol and heart issues

• Moderate intake of LA as a replacement of saturated fatty acids can reduce the total cholesterol and LDL levels in the blood.
   
• LA helps metabolise cholesterol by promoting the activity of CYP7. 
  
  
• As a response to the use of cholesterol in the liver, the hepatocytes increase the number and activity of LDLR. 
  
  
• Sterol regulatory element binding protein (SREBP) activates gene transcription and increases the uptake of cholesterol, fatty acid and triglyceride synthesis.
  
  
• This ability of LA to reduce LDL cholesterol is said to contribute to a lower risk of cardiovascular diseases.
  
  
• A study revealed that 5% energy replacement of saturated fatty acids by LA contributed to a 9% reduction in CHD.
  
  

3. Brain health

The role of LA in the brain is quite evidently low. Since the brain contains 2% of total fatty acids and in comparison of AA to DHA, the latter contributes to the majority of the brain’s fatty acids (40% of the brain’s fatty acids).

More than half of LA which enters the brain, helps in beta oxidation.

A study revealed that lowering dietary LA from 7% to 2% and an addition of 1.5g/day of EPA and DHA reduced the frequency of migraines and improved the quality of life. However, the clear effect has not been identified. 

Is omega 6 pro-inflammatory?

In general, inflammation is an essential bodily process that acts as a defence mechanism against pathogens and injury.  

In the early 1900’s when the consumption of butter and lard decreased, there was a twofold increase in the consumption of linoleic acid. Linoleic acids are present in vegetable oil, soybean oil, canola oil and corn oil. On average, western diets contain more than 40 grams of vegetable oil/day.

Up until 100 years ago, the omega 6:omega 3 ratio was <4:1. However, now most Western diets provide 20:1. This is due to the consumption of omega-6 oils. Soybean and safflower oil may provide ratios of 60:1 and 77:1.

The rise has also resulted in a rise in autoimmune, inflammatory and allergic diseases. Omega 6 has an inflammation-promoting effect while omega 3 has an anti-inflammatory effect.

Consumption of seed oils high in omega 6 (especially LA) can contribute to low-grade inflammation, oxidative stress, atherosclerosis and endothelial dysfunction. 

Dietary LA increases the expression of cyclooxygenase-2 (COX-2) in the aorta. This converts AA to proinflammatory cytokines. This is the reason why increasing the intake of LA can lower AA levels.

An AA-independent inflammation pathway is triggered by the consumption of omega-6 seed oils. This increasingly produces oxidised linoleic metabolites (OXLAM) and pro-inflammatory LA CYP-eicosanoids.

OXLAM formed from LA activates NF-kB and the production of proinflammatory cytokines, endothelial adhesion molecules, chemokines etc. which lead to atherosclerosis.

LA makes the environment of the endothelial cells to increase the risk of coronary heart disease (CHD)

How does omega 3 counteract inflammation?

Omega 3 can reduce inflammation caused as a result of AA metabolism.

When compared to high oleic sunflower oil (3.5g/day), fish oil (3.5g/day) can reduce acute phase reactants which implies fish oil activates the anti-inflammatory mechanism of early onset CHD.

How to improve intake of omega 3 in the diet?

• The PUFA in the diet must ideally be of the ratio omega 6:omega 3 – 4:1.
  
  
• Consult your doctor for omega-3 marine-based supplements.
  
  
• Increase consumption of seafood, fatty fish, crustaceans, shellfish etc.
  
  

Restrict consumption of industry-based omega-6 oils such as vegetable oils, corn oils, soybean oil, cottonseed oil, etc. and choose whole foods rich in omega-6 oils such as nuts, seeds, vegetables, eggs etc.


Mayuri,
Dietetic Researcher, Simplyweight